Toothed-wheel pump



y 1933. w. DRYSDALE TOOTHED WHEEL PUMP Filed Sept. 21, 1931 Patented May 2, 1933 UNITED STATES PATENT, oF icE WILLIAM DRYSDALE, F YOKER, GLASGOW, SCOTLAND, ASSIGNOR TO DRYSDALE AND 7 COMPANY, LIMITED, 0F GLASGOW, SCOTLAND r 1 TOOTHED-WHEEL PUMP A uieauon filed September 21, 1931, Serial No.

. well adapted for supplying a small quantity of liquid at a high pressure. For such a duty the ordinary type of single-stage. toothedwheel pump is not suitable owing to the leak age losses which occur with high pressures. According to the present invention the fluid is raised in pressure in two stages, that is by toothed wheels in series; and a construction is employed which will be described in the following specification. The invention will be defined'in the annexed claims.

The accompanying drawing illustrates the carrying of the invention into effect.

Fig. 1 is a sectional elevation of a pump driven by an electric motor and constructed according to the invention. (The motor is not in section.) v

Fig. 2 is a section on the line AA of Fig. 1.

A main casing a is provided: This is of a nature suitable for supporting the driving motor which in the present case is an electric motor 6. Through the main casing passes the driving shaft 0 of the pump: This shaft is driven from the motor by a chain 03 running on sprocket wheels 6 and f on the motor shaft and pump shaft respectively.

Bolted to one end wall a of the main casing is a casing h which will be termed the enveloping casing. It is dome-shaped; it encloses the pump proper.

The pump proper consists of two sets of intermeshing toothed wheels. One set,viz.

m, nconstitutes a low-pressure pump: the other set,viz. r, sconstitutes a high-pres sure pump. One wheel of each of the two stages,--viz. the wheels m, rare mounted on the driving shaft 0. The other wheels, viz. n, s, are mounted on a shaft 0 which is not driven except by the intermeshing of the pump wheels. All the wheels are contained in an annular wheel-case t of I-section having an apertured web. This wheel-case is enclosed in the enveloping casing k with its inner end face abutting the end wall a. The two shafts 0, 0 traverse the apertures in the web of the wheel-case and are journalled at their outer ends in bearings u, '0 formed in a casting 'w which is spigoted at a: Within the 564,108, and in Great Britain October 31,1930.

enveloping casing It, said casting 'w forming a cover for the outer end face of the wheel case If. Inner bearings 2, 3 for the two shafts are provided in the main casing.

The suction inlet 4 and the discharge outlet 5 are formed in the main. casing and are located above the pump proper. The latter therefore remains always charged with liquid even although the said inlet and/or outlet are opened; and moreover this arrangement ensures that, when starting the pump, the latter being full of liquid, a powerful initial suction effect can be obtained.

The toothed wheels m, n, r, 8, may have ordinary straight parallel teeth or they may on the low-pressure wheel on the same shaft with a view to balancing end thrust.

A stuffing box 6 is provided on the driving shaft 0 inside the main casing. Owing to the location of the high-pressure and loW- pressure pumps, the latter being next the stuffing box, leakage is reduced to a minimum.

' In order however further to ensure free- 'dom from, or reduce, leakage, a balance duct 7 is takenf-rom the annular space 8 around the driving shaft between the stufiing box 6;

and thelow pressure pump and is led to the suction chamber 9 of the pump. A controlled leak-off device 10-not of novel construction-is provided onthis balance pipe.

fact is of importance from the points 'of view of convenience, saving of labour, and reduction of leakage.

The wheel case t is held in place as shown between the main casing a and the casting w. It, the wheel case, is not a structuralpart 1 of the machine, and it can therefore be formed of very hard metal-an important fact from the point of view of wear.

Various deviations in "construction from that described could be employedwithin the scope of the invention. For example the Owing to the arrangement of the envelopdrive from the motor shaft to the shaft 0 might be by gear wheels instead of a chain; and a motor other than an electric motor might be employed.

It is an advantage of the present invention that, owing to the division of the work into two stages, the load on the teeth of each wheel is very much less thanapproximately only half ofthat of a single-stage pump .of equal toothed-wheel form; The wear and tear on the rotors is thus greatly reduced,

a point of considerable importance.

A pump according to the present invention is specially adapted for dealing with fuel oil for discharging throughburners. It

is however applicable in, in general, all cases where the quantity of liquid is small and the pressure high.

Having thus, described my invention, what Iclaim ,as new and desire to secure by Letters Patent is 1. A two-stage pump comprising a main casing, a driving motor resting on said main casing, a dome-shaped casing removably securedto one end wall of said maincasing, an annular wheel-case of I-section having an apertured web and supported inside said dome-shaped casing with its inner end face abutting against said end wall, a pair of co- Vacting wheels forminga low-pressure pump ,carriedby said wheel-case on the inner side of said web, a pair of co-acting wheels forming a high-pressure pump in series with the first pump and carried by said wheelcase on the outer sideof said .web, shafts traversing the web apertures, one shaft passingthrough said main casing andcarry ng one wheel of the low-pressure pump and one wheel of the highpressure pump, and the other shaft carrying theother wheelofeach ,pu1np, means whereby theifirst mentioned shaft is drivenby said motor, inner bearings for said shafts within said main casing, and a cover appliedto ,theouter ,end face ofs'aid wheel-case, said cover being spigoted withinsaid dome-shaped casingand supporting the outerendsofsaidshafts.

'2. A two-stage pump comprising a main casing formed with a suction inlet and a discharge outlet, a driving motor resting on said 59 ,main casing, an.envelop-i n g casing bolted .to one end wall of said maincasing, an annular the other wheel of each pump, means whereby the first mentioned shaft is driven by said motor, inner bearings for said shafts within said main casing, a cover applied to the outer end face of said Wheel-case and supporting the outer ends of said shafts, a stuffing box on said first mentioned shaftw ithin said main casing, there being an annular space between said stuifing box and the low pressure pump, an a b a ce t onnecting s i annu space with the suction side of the pump.

3. A two-stage pump comprising a main casing, adriving motor resting on said main casing, a domed casing bolted to one end wall of said main casing, an annular-wheel-rcase of I-section having an apertured webandsupported inside said do'med casing with its inner end face abuttingagainst said end wall,

a pair .of coaacting wheels formin .d w-' pressure pump carried by said whee -case on 'theinner side' of said web, a pair 'of co-acting wheels forming a high-pressure pump in series with the first pump -and carried by said wheel-case on the outer side of said web, shafts traversing the web apertures, one shaft Pa s h g sa ma asi an car ying one wheelof ,the low pressure pump and one wheel of the high-pressur'e pump,and the other shaftcarrying the other wheel of each pump and beingidle', meanswhereby the first mentioned shaft is driven by said motor, a

casting covering the outer end face of said wheel-case, inner bearings forsaid shafts within said main casing,an'd outer bearings for said shafts withinsaid casting.

' I-hereby signmy name tothis specification.

WILLIAM, DRYSDALE- wheel-case of I-section having'an apertured web andsupportedinside said enveloping casing with its inner end faceabutting against said end wall, a pair of v co-acting wheels forming a low pressure"pumpcarriedby said wheel-case on the nner side of said web, a

pair of co-actingwheelsforming a high-preslsurepumpin series with the first pump and 90 carried bysaid wheelcase onltheoute r side 29 2 51 1? pump, a theobh r h ft ar yi 

